We request funding so that the console of the Varian Unity 500 MHz NMR spectrometer housed in the Yale Department of Molecular Biophysics and Biochemistry Bass Center can be replaced, and a cryoprobe purchased for that spectrometer. The Varian Inova console requested will replace a Unity console that was built ca. 1990, and was purchased by Yale, second hand, in 1995. Inova consoles have a more robust computer interface that requires fewer reboots, and that executes pulses, power level, phase changes and frequency changes more efficiently than Unity consoles. This upgrade should result in significantly improved implementations of pulse sequences. In addition, Inova consoles are compatible with Varian newest software, SPINCAD, which do3es not run on Unity or Unity plus systems. Thus this upgrade should ensure the usefulness of our 500 MHZ spectrometer for years to come. Last, but not least, replacement of the console in question will reduce the amount of instrument time lost for repair, which has become considerable because the Unity console is reaching the end of its useful life. The cryoprobe requested has recently been developed by Varian. Its major attraction is its high sensitivity, relative to room temperature probes. The sensitivity of the 500 MHz spectrometer equipped with a cryoprobe should be double the sensitivity observed with the best room temperature probe now available on the Yale 800 MHz spectrometer. There are several structural biology projects under consideration that demand this sensitivity because the molecules of interest aggregate at the concentrations required when standard probes are used.